Component carrier activation and deactivation using resource assignments

ABSTRACT

This invention relates to a proposal of an uplink resource assignment format and a downlink resource assignment format. Furthermore, the invention relates to the use of the new uplink/downlink resource assignments in methods for (de)activation of downlink component carrier(s) configured for a mobile terminal, a base station and a mobile terminal. To enable efficient and robust (de)activation of component carriers, while minimizing the signaling overhead, the invention proposes a new uplink/downlink resource assignment format that allow the activation/deactivation of individual downlink component carriers configured for a mobile. The new uplink or downlink resource assignment comprises an indication of the activation state of the configured downlink component carriers, i.e., indicate which downlink component carrier(s) is/are to be activated or deactivated. This indication is for example implemented by means of a bit-mask that indicates which of the configured uplink component carriers are to be activated respectively deactivated.

BACKGROUND Technical Field

This invention relates to the proposal of a new uplink resourceassignment format and a new downlink resource assignment format thatallow the activation/deactivation of individual downlink componentcarriers configured for a mobile terminal. Furthermore, the inventionrelates to the use of the new uplink/downlink resource assignments inmethods for (de)activation of downlink component carrier(s) configuredfor a mobile terminal, a base station and a mobile terminal.

Description of the Related Art Long Term Evolution (LTE)

Third-generation mobile systems (3G) based on WCDMA radio-accesstechnology are being deployed on a broad scale all around the world. Afirst step in enhancing or evolving this technology entails introducingHigh-Speed Downlink Packet Access (HSDPA) and an enhanced uplink, alsoreferred to as High Speed Uplink Packet Access (HSUPA), giving aradio-access technology that is highly competitive.

In order to be prepared for further increasing user demands and to becompetitive against new radio access technologies 3GPP introduced a newmobile communication system which is called Long Term Evolution (LTE).LTE is designed to meet the carrier needs for high speed data and mediatransport as well as high capacity voice support to the next decade. Theability to provide high bit rates is a key measure for LTE.

The work item (WI) specification on Long-Term Evolution (LTE) calledEvolved UMTS Terrestrial Radio Access (UTRA) and UMTS Terrestrial RadioAccess Network (UTRAN) is to be finalized as Release 8 (LTE). The LTEsystem represents efficient packet-based radio access and radio accessnetworks that provide full IP-based functionalities with low latency andlow cost. The detailed system requirements are given in. In LTE,scalable multiple transmission bandwidths are specified such as 1.4,3.0, 5.0, 10.0, 15.0, and 20.0 MHz, in order to achieve flexible systemdeployment using a given spectrum. In the downlink, Orthogonal FrequencyDivision Multiplexing (OFDM) based radio access was adopted because ofits inherent immunity to multipath interference (MPI) due to a lowsymbol rate, the use of a cyclic prefix (CP), and its affinity todifferent transmission bandwidth arrangements. Single-Carrier FrequencyDivision Multiple Access (SC-FDMA) based radio access was adopted in theuplink, since provisioning of wide area coverage was prioritized overimprovement in the peak data rate considering the restrictedtransmission power of the user equipment (UE). Many key packet radioaccess techniques are employed including multiple-input multiple-output(MIMO) channel transmission techniques, and a highly efficient controlsignaling structure is achieved in LTE (Release 8).

LTE Architecture

The overall architecture is shown in FIG. 1 and a more detailedrepresentation of the E-UTRAN architecture is given in FIG. 2. TheE-UTRAN consists of eNodeB, providing the E-UTRA user plane(PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towardsthe user equipment (UE). The eNodeB (eNB) hosts the Physical (PHY),Medium Access Control (MAC), Radio Link Control (RLC), and Packet DataControl Protocol (PDCP) layers that include the functionality ofuser-plane header-compression and encryption. It also offers RadioResource Control (RRC) functionality corresponding to the control plane.It performs many functions including radio resource management,admission control, scheduling, enforcement of negotiated uplink Qualityof Service (QoS), cell information broadcast, ciphering/deciphering ofuser and control plane data, and compression/decompression ofdownlink/uplink user plane packet headers. The eNodeBs areinterconnected with each other by means of the X2 interface.

The eNodeBs are also connected by means of the S1 interface to the EPC(Evolved Packet Core), more specifically to the MME (Mobility ManagementEntity) by means of the S1-MME and to the Serving Gateway (SGW) by meansof the S1-U. The S1 interface supports a many-to-many relation betweenMMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user datapackets, while also acting as the mobility anchor for the user planeduring inter-eNodeB handovers and as the anchor for mobility between LTEand other 3GPP technologies (terminating S4 interface and relaying thetraffic between 2G/3G systems and PDN GW). For idle state userequipments, the SGW terminates the downlink data path and triggerspaging when downlink data arrives for the user equipment. It manages andstores user equipment contexts, e.g., parameters of the IP bearerservice, network internal routing information. It also performsreplication of the user traffic in case of lawful interception.

The MME is the key control-node for the LTE access-network. It isresponsible for idle mode user equipment tracking and paging procedureincluding retransmissions. It is involved in the beareractivation/deactivation process and is also responsible for choosing theSGW for a user equipment at the initial attach and at time of intra-LTEhandover involving Core Network (CN) node relocation. It is responsiblefor authenticating the user (by interacting with the HSS). TheNon-Access Stratum (NAS) signaling terminates at the MME and it is alsoresponsible for generation and allocation of temporary identities touser equipments. It checks the authorization of the user equipment tocamp on the service provider's Public Land Mobile Network (PLMN) andenforces user equipment roaming restrictions. The MME is the terminationpoint in the network for ciphering/integrity protection for NASsignaling and handles the security key management. Lawful interceptionof signaling is also supported by the MME. The MME also provides thecontrol plane function for mobility between LTE and 2G/3G accessnetworks with the S3 interface terminating at the MME from the SGSN. TheMME also terminates the S6a interface towards the home HSS for roaminguser equipments.

Component Carrier Structure in LTE (Release 8)

The downlink component carrier of a 3GPP LTE (Release 8) is subdividedin the time-frequency domain in so-called sub-frames. In 3GPP LTE(Release 8) each sub-frame is divided into two downlink slots as shownin FIG. 3, wherein the first downlink slot comprises the control channelregion (PDCCH region) within the first OFDM symbols. Each sub-frameconsists of a give number of OFDM symbols in the time domain (12 or 14OFDM symbols in 3GPP LTE (Release 8)), wherein each of OFDM symbol spansover the entire bandwidth of the component carrier. The OFDM symbols arethus each consists of a number of modulation symbols transmitted onrespective N_(RB) ^(DL)×N_(SC) ^(RB) subcarriers as also shown in FIG.4.

Assuming a multi-carrier communication system, e.g., employing OFDM, asfor example used in 3GPP Long Term Evolution (LTE), the smallest unit ofresources that can be assigned by the scheduler is one “resource block”.A physical resource block is defined as N_(symb) ^(DL) consecutive OFDMsymbols in the time domain and N_(SC) ^(RB) consecutive subcarriers inthe frequency domain as exemplified in FIG. 4. In 3GPP LTE (Release 8),a physical resource block thus consists of N_(symb) ^(DL)×N_(SC) ^(RB)resource elements, corresponding to one slot in the time domain and 180kHz in the frequency domain (for further details on the downlinkresource grid, see for example 3GPP TS 36.211, “Evolved UniversalTerrestrial Radio Access (E-UTRA); Physical Channels and Modulation(Release 8)”, version 8.9.0 or 9.0.0, section 6.2, available athttp://www.3gpp.org and incorporated herein by reference).

Layer 1/Layer 2 (L1/L2) Control Signaling

In order to inform the scheduled users about their allocation status,transport format and other data related information (e.g., HARQinformation, transmit power control (TPC) commands), L1/L2 controlsignaling is transmitted on the downlink along with the data. L1/L2control signaling is multiplexed with the downlink data in a sub-frame,assuming that the user allocation can change from sub-frame tosub-frame. It should be noted that user allocation might also beperformed on a TTI (Transmission Time Interval) basis, where the TTIlength is a multiple of the sub-frames. The TTI length may be fixed in aservice area for all users, may be different for different users, or mayeven by dynamic for each user. Generally, the L1/2 control signalingneeds only be transmitted once per TTI. The L1/L2 control signaling istransmitted on the Physical Downlink Control Channel (PDCCH). It shouldbe noted that in 3GPP LTE, assignments for uplink data transmissions,also referred to as uplink scheduling grants or uplink resourceassignments, are also transmitted on the PDCCH.

With respect to scheduling grants, the information sent on the Ll/L2control signaling may be separated into the following two categories.

Shared Control Information (SCI) carrying Cat 1 information

The shared control information part of the L1/L2 control signalingcontains information related to the resource allocation (indication).The shared control information typically contains the followinginformation:

-   -   A user identity indicating the user(s) that is/are allocated the        resources.    -   RB allocation information for indicating the resources (Resource        Blocks (RBs)) on which a user(s) is/are allocated. The number of        allocated resource blocks can be dynamic.    -   The duration of assignment (optional), if an assignment over        multiple sub-frames (or TTIs) is possible.

Depending on the setup of other channels and the setup of the DownlinkControl Information (DCI)—see below—the shared control information mayadditionally contain information such as ACK/NACK for uplinktransmission, uplink scheduling information, information on the DCI(resource, MCS, etc.).

Downlink Control Information (DCI) carrying Cat 2/3 information

The downlink control information part of the L1/L2 control signalingcontains information related to the transmission format (Cat 2information) of the data transmitted to a scheduled user indicated bythe Cat 1 information. Moreover, in case of using (Hybrid) ARQ as aretransmission protocol, the Cat 2 information carries HARQ (Cat 3)information. The downlink control information needs only to be decodedby the user scheduled according to Cat 1. The downlink controlinformation typically contains information on:

-   -   Cat 2 information: Modulation scheme, transport-block (payload)        size or coding rate, MIMO (Multiple Input Multiple        Output)-related information, etc. Either the transport-block (or        payload size) or the code rate can be signaled. In any case        these parameters can be calculated from each other by using the        modulation scheme information and the resource information        (number of allocated resource blocks)    -   Cat 3 information: HARQ related information, e.g., hybrid ARQ        process number, redundancy version, retransmission sequence        number

Downlink control information occurs in several formats that differ inoverall size and also in the information contained in its fields. Thedifferent DCI formats that are currently defined for LTE Release 8/9(3GPP LTE) are described in detail in 3GPP TS 36.212, “Multiplexing andchannel coding (Release 9)”, version 8.8.0 or 9.0.0, section 5.3.3.1(available at http://www.3gpp.org and incorporated herein by reference).

Downlink & Uplink Data Transmission

Regarding downlink data transmission, L1/L2 control signaling istransmitted on a separate physical channel (PDCCH), along with thedownlink packet data transmission. This L1/L2 control signalingtypically contains information on:

-   -   The physical resource(s) on which the data is transmitted (e.g.,        subcarriers or subcarrier blocks in case of OFDM, codes in case        of CDMA). This information allows the UE (receiver) to identify        the resources on which the data is transmitted.    -   When user equipment is configured to have a Carrier Indication        Field (CIF) in the L1/L2 control signaling this information        identifies the component carrier for which the specific control        signaling information is intended. This enables assignments to        be sent on one component carrier which are intended for another        component carrier (“cross-carrier scheduling”). This other,        cross-scheduled component carrier could be for example a        PDCCH-less component carrier, i.e., the cross-scheduled        component carrier does not carry any L1/L2 control signaling.    -   The Transport Format, which is used for the transmission. This        can be the transport block size of the data (payload size,        information bits size), the MCS (Modulation and Coding Scheme)        level, the Spectral Efficiency, the code rate, etc. This        information (usually together with the resource allocation        (e.g., the number of resource blocks assigned to the user        equipment)) allows the user equipment (receiver) to identify the        information bit size, the modulation scheme and the code rate in        order to start the demodulation, the de-rate-matching and the        decoding process. The modulation scheme may be signaled        explicitly.    -   Hybrid ARQ (HARQ) information:        -   HARQ process number: Allows the user equipment to identify            the hybrid ARQ process on which the data is mapped.            -   Sequence number or new data indicator (NDI): Allows the                user equipment to identify if the transmission is a new                packet or a retransmitted packet. If soft combining is                implemented in the HARQ protocol, the sequence number or                new data indicator together with the HARQ process number                enables soft-combining of the transmissions for a PDU                prior to decoding.            -   Redundancy and/or constellation version: Tells the user                equipment, which hybrid ARQ redundancy version is used                (required for de-rate-matching) and/or which modulation                constellation version is used (required for                demodulation).    -   UE Identity (UE ID): Tells for which user equipment the L1/L2        control signaling is intended for. In typical implementations        this information is used to mask the CRC of the L1/L2 control        signaling in order to prevent other user equipments to read this        information.

To enable an uplink packet data transmission, L1/L2 control signaling istransmitted on the downlink (PDCCH) to tell the user equipment about thetransmission details. This L1/L2 control signaling typically containsinformation on:

-   -   The physical resource(s) on which the user equipment should        transmit the data (e.g., subcarriers or subcarrier blocks in        case of OFDM, codes in case of CDMA).    -   When user equipment is configured to have a Carrier Indication        Field (CIF) in the L1/L2 control signaling this information        identifies the component carrier for which the specific control        signaling information is intended. This enables assignments to        be sent on one component carrier which are intended for another        component carrier. This other, cross-scheduled component carrier        may be for example a PDCCH-less component carrier, i.e., the        cross-scheduled component carrier does not carry any L1/L2        control signaling.    -   L1/L2 control signaling for uplink grants is sent on the DL        component carrier that is linked with the uplink component        carrier or on one of the several DL component carriers, if        several DL component carriers link to the same UL component        carrier.    -   The Transport Format, the user equipment should use for the        transmission. This can be the transport block size of the data        (payload size, information bits size), the MCS (Modulation and        Coding Scheme) level, the Spectral Efficiency, the code rate,        etc. This information (usually together with the resource        allocation (e.g., the number of resource blocks assigned to the        user equipment)) allows the user equipment (transmitter) to pick        the information bit size, the modulation scheme and the code        rate in order to start the modulation, the rate-matching and the        encoding process. In some cases the modulation scheme maybe        signaled explicitly.    -   Hybrid ARQ information:        -   HARQ Process number: Tells the user equipment from which            hybrid ARQ process it should pick the data.        -   Sequence number or new data indicator: Tells the user            equipment to transmit a new packet or to retransmit a            packet. If soft combining is implemented in the HARQ            protocol, the sequence number or new data indicator together            with the HARQ process number enables soft-combining of the            transmissions for a protocol data unit (PDU) prior to            decoding.        -   Redundancy and/or constellation version: Tells the user            equipment, which hybrid ARQ redundancy version to use            (required for rate-matching) and/or which modulation            constellation version to use (required for modulation).    -   UE Identity (UE ID): Tells which user equipment should transmit        data. In typical implementations this information is used to        mask the CRC of the L1/L2 control signaling in order to prevent        other user equipments to read this information.

There are several different flavors how to exactly transmit theinformation pieces mentioned above in uplink and downlink datatransmission. Moreover, in uplink and downlink, the L1/L2 controlinformation may also contain additional information or may omit some ofthe information. For example:

-   -   HARQ process number may not be needed, i.e., is not signaled, in        case of a synchronous HARQ protocol.    -   A redundancy and/or constellation version may not be needed, and        thus not signaled, if Chase Combining is used (always the same        redundancy and/or constellation version) or if the sequence of        redundancy and/or constellation versions is pre-defined.    -   Power control information may be additionally included in the        control signaling.    -   MIMO related control information, such as, e.g., pre-coding, may        be additionally included in the control signaling.    -   In case of multi-codeword MIMO transmission transport format        and/or HARQ information for multiple code words may be included.

For uplink resource assignments (on the Physical Uplink Shared Channel(PUSCH)) signaled on PDCCH in LTE, the L1/L2 control information doesnot contain a HARQ process number, since a synchronous HARQ protocol isemployed for LTE uplink. The HARQ process to be used for an uplinktransmission is given by the timing. Furthermore it should be noted thatthe redundancy version (RV) information is jointly encoded with thetransport format information, i.e., the RV info is embedded in thetransport format (TF) field. The Transport Format (TF) respectivelymodulation and coding scheme (MCS) field has for example a size of 5bits, which corresponds to 32 entries. Three TF/MCS table entries arereserved for indicating redundancy versions (RVs) 1, 2 or 3. Theremaining MCS table entries are used to signal the MCS level (TBS)implicitly indicating RV0. The size of the CRC field of the PDCCH is 16bits.

For downlink assignments (PDSCH) signaled on PDCCH in LTE the RedundancyVersion (RV) is signaled separately in a two-bit field. Furthermore themodulation order information is jointly encoded with the transportformat information. Similar to the uplink case there is 5 bit MCS fieldsignaled on PDCCH. Three of the entries are reserved to signal anexplicit modulation order, providing no Transport format (Transportblock) info. For the remaining 29 entries modulation order and Transportblock size info are signaled.

Physical Downlink Control Channel (PDCCH)

The physical downlink control channel (PDCCH) carries the L1/L2 controlsignaling, i.e., transmit power control commands and the schedulinggrants for allocating resources for downlink or uplink datatransmission. To be more precise, the downlink control channelinformation (i.e., the DCI contents, respectively, the L1/L2 controlsignaling information) is mapped to its corresponding physical channel,the PDCCH. This “mapping” includes the determination of a CRC attachmentfor the downlink control channel information, which is a CRC calculatedon the downlink control channel information being masked with an RNTI,as will explained below in more detail. The downlink control channelinformation and its CRC attachment are then transmitted on the PDCCH(see 3GPP TS 36.212, sections 4.2 and 5.3.3).

Each scheduling grant is defined based on Control Channel Elements(CCEs). Each CCE corresponds to a set of Resource Elements (REs). In3GPP LTE, one CCE consists of 9 Resource Element Groups (REGs), whereone REG consists of four REs.

The PDCCH is transmitted on the first one to three OFDM symbols within asub-frame. For a downlink grant on the physical downlink shared channel(PDSCH), the PDCCH assigns a PDSCH resource for (user) data within thesame sub-frame. The PDCCH control channel region within a sub-frameconsists of a set of CCE where the total number of CCEs in the controlregion of sub-frame is distributed throughout time and frequency controlresource. Multiple CCEs can be combined to effectively reduce the codingrate of the control channel. CCEs are combined in a predetermined mannerusing a tree structure to achieve different coding rate.

In 3GPP LTE (Release 8/9), a PDCCH can aggregate 1, 2, 4 or 8 CCEs. Thenumber of CCEs available for control channel assignment is a function ofseveral factors, including carrier bandwidth, number of transmitantennas, number of OFDM symbols used for control and the CCE size, etc.Multiple PDCCHs can be transmitted in a sub-frame.

Downlink control channel information in form of DCI transports downlinkor uplink scheduling information, requests for aperiodic CQI reports, oruplink power control commands for one RNTI (Radio Network TerminalIdentifier). The RNTI is a unique identifier commonly used in 3GPPsystems like 3GPP LTE (Release 8/9) for destining data or information toa specific user equipment. The RNTI is implicitly included in the PDCCHby masking a CRC calculated on the DCI with the RNTI—the result of thisoperation is the CRC attachment mentioned above. On the user equipmentside, if decoding of the payload size of data is successful, the userequipment detects the DCI to be destined to the user equipment bychecking whether the CRC on the decoded payload data using the“unmasked” CRC (i.e., after removing the masking using the RNTI) issuccessful. The masking of the CRC code is for example performed byscrambling the CRC with the RNTI.

In 3GPP LTE (Release 8) the following different DCI formats are defined:

-   -   Uplink DCI formats:        -   Format 0 used for transmission of UL SCH assignments        -   Format 3 is used for transmission of TPC commands for PUCCH            and PUSCH with 2 bit power adjustments (multiple UEs are            addressed)        -   Format 3A is used for transmission of TPC commands for PUCCH            and PUSCH with single bit power adjustments (multiple UEs            are addressed)    -   Downlink DCI formats:        -   Format 1 used for transmission of DL SCH assignments for            SIMO operation        -   Format 1A used for compact transmission of DL SCH            assignments for SIMO operation        -   Format 1B used to support closed loop single rank            transmission with possibly contiguous resource allocation        -   Format 1C is for downlink transmission of paging, RACH            response and dynamic BCCH scheduling        -   Format 1D is used for compact scheduling of one PDSCH            codeword with precoding and power offset information        -   Format 2 is used for transmission of DL-SCH assignments for            closed-loop MIMO operation        -   Format 2A is used for transmission of DL-SCH assignments for            open-loop MIMO operation

For further information on the LTE physical channel structure indownlink and the PDSCH and PDCCH format, see Stefania Sesia et al.,“LTE—The UMTS Long Term Evolution”, Wiley & Sons Ltd., ISBN978-0-47069716-0, April 2009, sections 6 and 9.

Blind Decoding of PDCCHs at the User Equipment

In 3GPP LTE (Release 8/9), the user equipment attempts to detect the DCIwithin the PDCCH using so-called “blind decoding”. This means that thereis no associated control signaling that would indicate the CCEaggregation size or modulation and coding scheme for the PDCCHs signaledin the downlink, but the user equipment tests for all possiblecombinations of CCE aggregation sizes and modulation and coding schemes,and confirms that successful decoding of a PDCCH based on the RNTI. Tofurther limit complexity a common and dedicated search space in thecontrol signaling region of the LTE component carrier is defined inwhich the user equipment searches for PDCCHs.

In 3GPP LTE (Release 8/9) the PDCCH payload size is detected in oneblind decoding attempt. The user equipment attempts to decode twodifferent payload sizes for any configured transmission mode, ashighlighted in Table 1 below. Table 1 shows that payload size X of DCIformats 0, 1A, 3, and 3A is identical irrespective of the transmissionmode configuration. The payload size of the other DCI format depends onthe transmission mode.

TABLE 1 DCI Formats payload size transmission payload size X differentfrom X mode 0/1A/3/3A 1C broadcast/unicast/ paging/power control 1 Mode1 DL TX modes 1 Mode 2 2A Mode 3 2 Mode 4 1B Mode 5 1D Mode 6 1 Mode 7 1Mode 1 SPS-Modes 1 Mode 2 2A Mode 3 2 Mode 4 1 Mode 7

Accordingly, the user equipment can check in a first blind decodingattempt the payload size of the DCI. Furthermore, the user equipment isfurther configured to only search for a given subset of the DCI formatsin order to avoid too high processing demands.

Further Advancements for LTE (LTE-A)

The frequency spectrum for IMT-Advanced was decided at the WorldRadiocommunication Conference 2007 (WRC-07). Although the overallfrequency spectrum for IMT-Advanced was decided, the actual availablefrequency bandwidth is different according to each region or country.Following the decision on the available frequency spectrum outline,however, standardization of a radio interface started in the 3rdGeneration Partnership Project (3GPP). At the 3GPP TSG RAN #39 meeting,the Study Item description on “Further Advancements for E-UTRA(LTE-Advanced)” was approved in the 3GPP. The study item coverstechnology components to be considered for the evolution of E-UTRA,e.g., to fulfill the requirements on IMT-Advanced. Two major technologycomponents which are currently under consideration for LTE-A aredescribed in the following.

Carrier Aggregation in LTE-A for Support of Wider Bandwidth

In Carrier Aggregation (CA), two or more Component Carriers (CCs) areaggregated in order to support wider transmission bandwidths up to 100MHz. All component carriers can be configured to be 3GPP LTE (Release8/9) compatible, at least when the aggregated numbers of componentcarriers in the uplink and the downlink are the same. This does notnecessarily mean that all component carriers need to be compatible to3GPP LTE (Release 8/9).

A user equipment may simultaneously receive or transmit on one ormultiple component carriers. On how many component carriers simultaneousreception/transmission is possible, is depending on the capabilities ofa user equipment.

A 3GPP LTE (Release 8/9) compatible user equipment can receive andtransmit on a single CC only, provided that the structure of the CCfollows the 3GPP LTE (Release 8/9) specifications, while a 3GPP LTE-A(Release 10) compatible user equipment with reception and/ortransmission capabilities for carrier aggregation can simultaneouslyreceive and/or transmit on multiple component carriers.

Carrier aggregation is supported for both contiguous and non-contiguouscomponent carriers with each component carrier limited to a maximum of110 Resource Blocks in the frequency domain using the 3GPP LTE (Release8/9) numerology.

It is possible to configure a 3GPP LTE-A (Release 10) compatible userequipment to aggregate a different number of component carriersoriginating from the same eNodeB (base station) and of possiblydifferent bandwidths in the uplink and the downlink. In a typical TDDdeployment, the number of component carriers and the bandwidth of eachcomponent carrier in uplink and downlink is the same. Component carriersoriginating from the same eNodeB need not to provide the same coverage.

The spacing between center frequencies of contiguously aggregatedcomponent carriers shall be a multiple of 300 kHz. This is in order tobe compatible with the 100 kHz frequency raster of 3GPP LTE (Release8/9) and at the same time preserve orthogonality of the subcarriers with15 kHz spacing. Depending on the aggregation scenario, the n×300 kHzspacing can be facilitated by insertion of a low number of unusedsubcarriers between contiguous component carriers.

The nature of the aggregation of multiple carriers is only exposed up tothe MAC layer. For both uplink and downlink there is one HARQ entityrequired in MAC for each aggregated component carrier. There is (in theabsence of SU-MIMO for uplink) at most one transport block per componentcarrier. A transport block and its potential HARQ retransmissions needto be mapped on the same component carrier.

The Layer 2 structure with activated carrier aggregation is shown inFIG. 5 and FIG. 6 for the downlink and uplink respectively.

When carrier aggregation is configured, the user equipment only has oneRadio Resource Control (RRC) connection with the network. One cell—the“special cell”—provides the security input and the Non-Access Stratum(NAS) mobility information (e.g., TAI). There is only one special cellper user equipment in connected mode.

After RRC connection establishment to the special cell, thereconfiguration, addition and removal of component carriers can beperformed by RRC. At intra-LTE handover, RRC can also add, remove, orreconfigure component carriers for usage in the target cell. When addinga new component carrier, dedicated RRC signaling is used for sendingcomponent carriers' system information which is necessary for componentcarrier transmission / reception, similar to a handover in 3GPP LTE(Release 8/9).

When a user equipment is configured with carrier aggregation there isone pair of uplink and downlink component carriers that is alwaysactivate. The downlink component carrier of that pair might be alsoreferred to as ‘DL anchor carrier’. Same applies also for the uplink.

When carrier aggregation is configured, a user equipment may bescheduled over multiple component carriers simultaneously but at mostone random access procedure shall be ongoing at any time. Cross-carrierscheduling allows the PDCCH of a component carrier to schedule resourceson another component carrier. For this purpose a component carrieridentification field is introduced in the respective DCI formats.

A linking between uplink and downlink component carriers allowsidentifying the uplink component carrier for which the grant applieswhen there is no-cross-carrier scheduling.

The linkage of downlink component carriers to uplink component carriersdoes not necessarily need to be one to one. In other words, more thanone downlink component carrier can link to the same uplink componentcarrier. At the same time, a downlink component carrier can only link toone uplink component carrier. FIG. 7 exemplarily shows possible linkagesbetween downlink and uplink component carriers. While on the left sideall downlink component carriers are linked to the same uplink componentcarrier, on the right side downlink component carriers 1 and 2 arelinked to uplink component carrier 1 and downlink component carrier 3 islinked to uplink component carrier 2.

DRX and Carrier Aggregation

In order to provide reasonable battery consumption of user equipment3GPP LTE (Release 8/9) as well as 3GPP LTE-A (Release 10) provides aconcept of discontinuous reception (DRX).

For this concept the following terms describe the user equipment's statein terms of DRX.

-   -   on-duration: duration in downlink sub-frames that the user        equipment waits for, after waking up from DRX, to receive        PDCCHs. If the user equipment successfully decodes a PDCCH, the        user equipment stays awake and starts the inactivity timer;    -   inactivity-timer: duration in downlink sub-frames that the user        equipment waits to successfully decode a PDCCH, from the last        successful decoding of a PDCCH, failing which it re-enters DRX.        The user equipment shall restart the inactivity timer following        a single successful decoding of a PDCCH for a first transmission        only (i.e., not for retransmissions).    -   active-time: total duration that the user equipment is awake.        This includes the “on-duration” of the DRX cycle, the time user        equipment is performing continuous reception while the        inactivity timer has not expired and the time user equipment is        performing continuous reception while waiting for a downlink        retransmission after one HARQ RTT (Round Trip Time). Based on        the above the minimum active time is of length equal to        on-duration, and the maximum is undefined (infinite);

There is only one DRX cycle per user equipment. All aggregated componentcarriers follow this DRX pattern.

In order to allow for further battery saving optimization, a furtherstep of activation/deactivation of component carriers is introduced.Essentially a downlink component carrier could be in one of thefollowing three states: non-configured, configured but deactivated andactive. When a downlink component carrier is configured but deactivated,the user equipment does not need to receive the corresponding PDCCH orPDSCH, nor is it required to perform CQI measurements. Conversely, whena downlink component carrier is active, the user equipment shall receivePDSCH and PDCCH (if present), and is expected to be able to perform CQImeasurements. After configuration of component carriers in order to havePDCCH and PDSCH reception on a downlink component as described above,the downlink component carrier needs to be transitioned from configuredbut deactivated to active state.

In the uplink however, a user equipment is always required to be able totransmit on PUSCH on any configured uplink component carrier whenscheduled on the corresponding PDCCH (i.e., there is no explicitactivation of uplink component carriers).

For user equipment power-saving purposes, it is crucial that additionalcomponent carriers can be de-activated and activated in an efficient andfast way. With bursty data-transmission, it is imperative thatadditional component carriers can be activated and de-activated quickly,such that both the gains of high bit-rates can be utilized, and batterypreservation can be supported. As described before user equipments willnot perform and report CQI measurements on configured but deactivateddownlink component carriers but only radio resource management relatedmeasurements like RSRP (Reference Signal Received Power) and RSRQ(Reference Signal Received Quality) measurements. Hence when activatinga downlink component carrier, it is important that eNodeB acquiresquickly CQI information for the newly activated component carrier(s) inorder to being able to select an appropriate MCS for efficient downlinkscheduling. Without CQI information eNodeB does not have knowledge aboutuser equipment's downlink channel state and might only select a ratherconservative MCS for downlink data transmission which would in turn leadto some resource utilization inefficiency.

In order to acquire CQI information quickly, eNodeB can schedule anaperiodic CQI by means of an uplink scheduling grant. The aperiodic CQIwould be transmitted on the physical uplink shared channel (PUSCH).Therefore in order to activate a configured downlink component carrier,eNodeB would need to issue essentially two grants (PDCCH) to the UE, onedownlink PDCCH in order to indicate the activation of a downlinkcomponent carrier and one uplink PDCCH which schedules uplink resourcesfor the transmission of the aperiodic CQI. Furthermore both PDCCH has tobe sent respectively received in the same TTI in order to ensure, thatuser equipment measures and reports CQI information for the correctdownlink component carrier, i.e., the downlink component carrier whichwill be activated.

The correct reception of the aperiodic CQI can serve as anacknowledgement for the downlink activation command, i.e., whenaperiodic CQI has been received eNodeB assumes that user equipment hasactivated the downlink component carrier indicated in the downlinkPDCCH.

As it becomes apparent, the main drawback of the above describedcomponent carrier activation method is, that two PDCCHs are required inorder to activate a downlink component carrier. Furthermore due to thefact that the two PDCCHs need to be received/sent simultaneously,certain error cases may occur in the presence of PDCCH loss.

In case only the downlink “activation” PDCCH is lost, user equipmentwill not activate the downlink component carrier. However based onreceived CQI information eNB erroneously assumes downlink activation hassucceeded.

In the second error case when only the uplink PDCCH which requests theaperiodic CQI is lost, eNodeB does not acquire CQI and erroneouslyassumes that downlink activation has failed.

BRIEF SUMMARY

One object of the invention is to overcome at least one of the describedproblems. Furthermore, it is another object of the invention to enableefficient and robust (de)activation of component carriers, whileminimizing the signaling overhead.

The object is solved by the subject matter of the independent claims.Advantageous embodiments of the invention are subject to the dependentclaims.

A first aspect of the invention is the proposal of a new uplink resourceassignment format and a new downlink resource assignment format thatallow the activation/deactivation of individual downlink componentcarriers configured for a mobile terminal (referred to as user equipmentin the 3GPP terminology). The new uplink or downlink resource assignmentcomprises an indication of the activation state of the configureddownlink component carriers, i.e., indicate which downlink componentcarrier(s) is/are to be activated or deactivated. This indication is forexample implemented by means of a bit-mask that indicates which of theconfigured uplink component carriers are to be activated respectivelydeactivated.

Furthermore, as to the proposal of the new downlink resource assignmentformat, a single downlink resource assignment can be used to(de)activate downlink component carrier(s) and to simultaneously assigndownlink resources on an activated downlink component carrier (i.e., adownlink component carrier already in active state at the time ofreceiving the downlink resource assignment).

In one exemplary implementation of the format in a 3GPP basedcommunication system using carrier aggregation in the downlink, such as3GPP LTE-A (Release 10) or future releases using carrier aggregation inthe downlink, the new resource assignment format may be considered anextension to existing DCI formats or a new DCI format.

In another exemplary implementation, each of the bits in the bit-mask isassociated to a respective configured downlink component carrier, andindicates its activation state. By checking this bit-mask comprised inthe uplink or downlink resource assignment, the mobile terminal candetermine for each of the configured downlink component carriers,whether the activation state of the respective downlink componentcarrier is changed, i.e., which one or ones of the configured downlinkcomponent carriers need to be activated or deactivated.

Furthermore, in a more advanced exemplary implementation, the uplinkresource assignment including the component carrieractivation/deactivation information may also instruct the mobileterminal to send a channel quality measurement on the newly activatedcomponent carriers (i.e., those component carrier(s) for which the statehas changed from deactivated to activated). Accordingly, the mobileterminal performs a channel quality measurement for each newly activatedcomponent carrier and sends the result of the measurement to the basestation (referred to as eNodeB in the 3GPP terminology) on the uplinkresources that have been assigned to the mobile terminal by means of theuplink resource assignment. The transmission of the channel qualitymeasurement result(s) indicates to the base station that the mobileterminal has successfully received the uplink resource assignment,respectively, has successfully activated/deactivated the configureddownlink component carriers. Hence, the transmission of the channelquality measurement result(s) can be considered an acknowledgment of theuplink resource assignment, respectively the activation/deactivation ofconfigured downlink component carriers by the mobile terminal.

In one embodiment of the invention, the new format of the uplinkresource assignment is used in a method for (de)activating downlinkcomponent carriers in a mobile communication system using componentcarrier aggregation. In this method performed by a mobile terminal, themobile terminal receives on a downlink component carrier, an uplinkresource assignment for assigning uplink resources to the mobileterminal. The uplink resource assignment comprises a bit-mask indicatingwhich of plural configured downlink component carriers are to beactivated, respectively deactivated. The mobile terminal activates ordeactivates the configured downlink component carriers according to thebit-mask comprised in the uplink resource assignment.

In a further embodiment of the invention, the mobile terminal performs achannel quality measurement for each downlink component carrier newlyactivated by the uplink resource assignment (i.e., the downlinkcomponent carrier(s) that is/are not yet activated at the time ofreceiving the uplink resource assignment), and transmits the channelquality measurement(s) for the activated downlink component carrier(s)on assigned uplink resources. Alternatively, according to anotherembodiment of the invention, the mobile terminal may also transmitscheduling-related information for uplink scheduling on the assigneduplink resources.

In both cases, the uplink transmission on the assigned uplink resourcemay be considered and acknowledgement of the (successful) reception ofthe uplink resource assignment or successful (de)activation of thedownlink component carriers.

In another exemplary embodiment, the new uplink resource assignmentformat is used in another method for (de)activating downlink componentcarriers in a mobile communication system using component carrieraggregation that is performed by a base station, the base stationtransmits an uplink resource assignment to a mobile terminal forassigning uplink resources to a mobile terminal. The uplink resourceassignment is transmitted on an active configured downlink componentcarrier to the mobile terminal. Moreover, besides the uplink assignmentto the mobile terminal, the uplink resource assignment comprises abit-mask indicating which of plural configured downlink componentcarriers are to be activated, respectively deactivated. In response tohis uplink resource assignment, the base station receives anacknowledgment for the successful reception of the uplink resourceassignment or successful (de)activation of the downlink componentcarriers. The acknowledgment is transmitted on the assigned uplinkresources. Furthermore, the acknowledgement is for example received inform of a channel quality measurement(s) for newly activated downlinkcomponent carrier(s) or alternatively in form of scheduling relatedinformation transmitted from the mobile terminal to the base station.

In another embodiment of the invention, the new format of the downlinkresource assignment is used in a method for (de)activating downlinkcomponent carriers in a mobile communication system using componentcarrier aggregation. In this method performed by a mobile terminal, themobile terminal receives on a downlink component carrier, a downlinkresource assignment for assigning downlink resources to the mobileterminal. The downlink resource assignment comprises an indication thatindicating which of plural configured downlink component carriers are tobe activated, respectively deactivated. The mobile terminal activates ordeactivates the configured downlink component carriers according to theindication comprised in the uplink resource assignment. The indicationmay be for example realized in form of a bit-mask.

Furthermore, the mobile terminal further receives the downlink dataindicated in the downlink resource assignment. Please note that theassigned downlink resources are on a downlink component carrier alreadyin active state at the time of receiving the downlink resourceassignment—which could be the downlink component carrier on which thedownlink resource assignment has been received or a cross-scheduledother downlink component carrier in active state.

Moreover, in a further exemplary embodiment of the invention, thedownlink resource assignment and the downlink data on the assigneddownlink resources are received within a single sub-frame.

In the methods described above, according to another embodiment of theinvention, the uplink resource assignment comprises a CRC field that ismasked with a radio network temporary identifier (RNTI) assigned to themobile terminal for the activation and deactivation of downlinkcomponent carriers. The use of a “special” RNTI assigned to the mobileterminal for the activation and deactivation of downlink componentcarriers the base station may for example indicate the format of thereceived uplink resource assignment to the mobile terminal. The specialRNTI for the activation and deactivation of downlink component carriersis advantageously mobile terminal specific, so that no furtherindication of the intended receiver of the uplink or downlink resourceassignment is needed.

As mentioned above, in the context of implementing the concepts of thisinvention in a 3GPP based communication system using carrier aggregationin the downlink, the uplink resource assignment as well as the downlinkresource assignment proposed herein can be considered a “special” DCIformat of L1/L2 control information. As plural DCI formats may existthat have the same size, the RNTI assigned to the mobile terminal forthe activation and deactivation of downlink component carriers may be aformat indication to distinguish the combined uplink assignmentincluding information on the downlink component carrier activation statefrom “pure” resource assignments on an uplink, respectively downlinkcomponent carrier.

Staying for exemplary purposes at the exemplary implementation of theconcepts of the invention in the 3GPP context, the uplink resourceassignment could be for example reusing the 3GPP LTE (Release 8/9) DCIformat 0, wherein the bits of new data indicator (NDI), the TPC commandfield and the CQI request flag of 3GPP LTE DCI format 0 are reused toindicate the bit-mask. Alternatively, in another exemplaryimplementation and in order to further include and an indication whetherthe mobile terminal is to send channel quality measurement for the newlyactivated downlink component carrier(s) to the uplink resourceassignment, the bits of new data indicator (NDI), the TPC command field,the CQI request flag and one bit of the modulation and coding schemefield of 3GPP LTE DCI format 0 may be reused to indicate the bit-maskand the indication whether the mobile terminal is to send channelquality measurement for the newly activated downlink componentcarrier(s).

In a further embodiment of the invention, and still in the context ofimplementing the concepts of the invention in a 3GPP based communicationsystem using carrier aggregation in the downlink, the uplink resourceassignment is considered downlink control information (DCI) for FDDoperation and consists of:

-   -   a format flag for distinguishing DCI formats, which are defined        to have the same number of bits/size,    -   a hopping flag indicating whether or not the mobile terminal        should employ uplink resource hopping,    -   a resource block assignment field assigning the uplink resources        on the PUSCH to the mobile terminal,    -   a modulation and coding scheme field that is indicating the        modulation scheme, coding rate and the redundancy version for        the transmission on the assigned resources on the PUSCH,    -   a DMRS field for configuring the cyclic shift applied to the        reference symbol sequence,    -   a component carrier (de)activation field that is indicating for        each of a plurality of downlink component carriers, whether the        respective downlink component carrier is to be activated or        deactivated by means of the bit-mask, and    -   if required (i.e., optionally) one or more padding bit(s) to        align the size of the dedicated control information to a        predetermined number of bits.

In another alternative embodiment of the invention, the uplink resourceassignment further—i.e., in addition to the fields mentionedabove—consists of a carrier indicator field for indicating on which ofplural uplink component carriers the uplink resources are assigned. Thisimplementation may be useful in a 3GPP LTE-A (Release 10) wherecross-carrier scheduling can be employed.

In both exemplary uplink assignment formats discussed in the precedingparagraphs, the uplink resource assignment may optionally furtherconsists of a CQI flag for indicating whether the mobile terminal is tosend channel quality measurement for the newly activated downlinkcomponent carrier(s). Please note that this CQI flag is not necessarilythe CQI flag as known from the 3GPP LTE (Release 8/9) DCI format 0. Inan alternative implementation, the two uplink resource assignmentformats discussed in the preceding paragraphs may optionally make use ofat least one codepoint representable in the modulation and coding schemefield to indicate whether the mobile terminal is to send channel qualitymeasurement for the newly activated downlink component carrier(s).

In another exemplary embodiment related to the implementation of theproposed downlink assignment in the 3GPP context, the downlink resourceassignment could be for example reusing the 3GPP LTE (Release 8/9) DCIformat 1A. For example, the bit(s) of new data indicator (NDI) and/orthe TPC command for PUCCH field of 3GPP LTE DCI format 1A may be reusedto indicate the activation state of the downlink component carriers. Forexample, if redefining the NDI flag as a new downlink component carrier(DL CC) (de)activation flag, this new flag could be used to activate ordeactivate all downlink component carriers (except for one of thedownlink component carriers, e.g., the anchor carrier, that is alwaysactivated). If the TPC command for PUCCH field and the NDI flag arereused, it would be possible to indicate by using one bit the activationstate (active or configured but deactivated) for one component carrier,and to use the remaining available bits for indicating the one downlinkcomponent carrier to which the (de)activation pertains.

In a further embodiment of the invention, the uplink, respectivelydownlink resource assignment comprises a CRC field that is masked with aradio network temporary identifier (RNTI) assigned to the mobileterminal for resource assignments to the mobile terminal, and at leastone of the codepoints of a carrier indicator field (CIF) of the uplink,respectively downlink resource assignment is indicating whether theuplink, respectively downlink resource assignment is indicating thebit-mask for (de)activating the configured downlink component carriers,or whether the uplink resource assignment is not used for (de)activationof the configured downlink component carriers, respectively only assignsuplink, respectively downlink resources.

A further aspect of the invention is the implementation of the differentmethods for (de)activating downlink component carriers in a mobilecommunication system using component carrier aggregation according tothe various embodiments discussed herein in hardware and software, orcombinations thereof. In this context, another embodiment of theinvention provides a mobile terminal for use in a mobile communicationsystem using component carrier aggregation. The mobile terminalcomprises a receiver for receiving on a downlink component carrier, anuplink resource assignment for assigning uplink resources to the mobileterminal, wherein the uplink resource assignment is comprising abit-mask indicating which of plural configured downlink componentcarriers are to be activated, respectively deactivated. Furthermore, themobile terminal comprises a processor for activating or deactivating theconfigured downlink component carriers according to the bit-maskcomprised in the uplink resource assignment.

In a furthermore embodiment of the invention, the mobile terminal alsocomprises a channel quality measuring unit for performing a channelquality measurement for each downlink component carrier newly activatedby the uplink resource assignment, and a transmitter for transmittingthe channel quality measurement(s) for the activated downlink componentcarrier(s) on assigned uplink resources.

Another embodiment of the invention provides a further mobile terminalfor use in a mobile communication system using component carrieraggregation. The mobile terminal comprises a receiver for receiving on adownlink component carrier, an downlink resource assignment forassigning downlink resources to the mobile terminal, wherein the uplinkresource assignment is comprising a bit-mask indicating which of pluralconfigured downlink component carriers are to be activated, respectivelydeactivated. The receiver of the mobile terminal further receives thedownlink data on the downlink resources assigned by the downlinkresource assignment. Furthermore, the mobile terminal comprises aprocessor for activating or deactivating the configured downlinkcomponent carriers according to the bit-mask comprised in the uplinkresource assignment.

In another embodiment of the invention, the mobile terminal receives thedownlink data using one of plural HARQ processes of a HARQ protocol, andassumes a known value for the new data indicator (NDI) for thetransmission of the downlink data. According to another embodiment ofthe invention the uplink, respectively downlink resource assignment isreceived within a control signaling region of a sub-frame. Accordingly,the mobile terminal (or more accurately its receiver) may perform ablind detection of the resource assignment within the control signalingregion of the sub-frame.

In a further embodiment of the invention, the mobile terminal'sprocessor further obtains a masked CRC code from a CRC field of theuplink, respectively downlink resource assignment, de-masks the maskedCRC code with a radio network temporary identifier (RNTI) assigned tothe mobile terminal for the activation and deactivation of downlinkcomponent carriers to thereby obtain a CRC code, and verifies successfulblind detection of the resource assignment based on the CRC code.

Furthermore, another embodiment of the invention provides a base stationfor in a mobile communication system using component carrieraggregation. The base station comprises a transmitter for transmittingon an active configured downlink component carrier an uplink resourceassignment to a mobile terminal for assigning uplink resources to amobile terminal, wherein the uplink resource assignment is comprising abit-mask indicating which of plural configured downlink componentcarriers are to be activated, respectively deactivated. Moreover, thebase station comprises a receiver for receiving on the assigned uplinkresources an acknowledgment for the successful reception of the uplinkresource assignment or successful (de)activation of the downlinkcomponent carriers, wherein the acknowledgement is received in form of achannel quality measurement(s) for the newly activated downlinkcomponent carrier(s).

With respect to the assignment of downlink resources, a furtherembodiment of the invention provides a base station for in a mobilecommunication system using component carrier aggregation. The basestation comprises a transmitter for transmitting on an active configureddownlink component carrier a downlink resource assignment to a mobileterminal for assigning downlink resources to a mobile terminal, whereinthe downlink resource assignment is comprising a bit-mask indicatingwhich of plural configured downlink component carriers are to beactivated, respectively deactivated. Moreover, the base station furthertransmits within the same sub-frame as the downlink resource assignmentand on the assigned downlink resources downlink data (e.g., a transportblock) to the mobile terminal.

In another embodiment of the invention, the base station uses one ofplural HARQ processes of a HARQ protocol for the transmission of thedownlink data, and assumes a known value for the new data indicator(NDI) for the transmission of the downlink data.

The base station according to a more specific embodiment of theinvention further comprises a processor for generating a CRC field forthe uplink, respectively downlink resource assignment and for maskingthe CRC field with a radio network temporary identifier (RNTI) assignedto the mobile terminal for the activation and deactivation of downlinkcomponent carriers prior to the transmission of the uplink, respectivelydownlink resource assignment to the mobile terminal.

Moreover, the base station's transmitter may transmit the radio networktemporary identifier (RNTI) assigned to the mobile terminal for theactivation and deactivation of downlink component carriers to the mobileterminal.

As mentioned above, an aspect of the invention is the implementation ofthe methods for (de)activating downlink component carriers in a mobilecommunication system using component carrier aggregation according tothe various embodiments discussed herein in software and its storage oncomputer-readable storage media.

According to a further embodiment, the invention provides acomputer-readable medium that stores instructions that, when executed bya processor of a mobile terminal, cause the mobile terminal to performone of methods for (de)activating downlink component carriers in amobile communication system using component carrier aggregationaccording to one of the various embodiments discussed herein. Theexecution of the instructions may for example cause the mobile terminalto receive on a downlink component carrier, an resource assignment forassigning uplink or downlink resources to the mobile terminal, whereinthe resource assignment is indicating which of plural configureddownlink component carriers are to be activated, respectivelydeactivated, and further to activate or deactivate the configureddownlink component carriers according to the bit-mask comprised in theuplink resource assignment.

Another embodiment of the invention is providing a computer-readablemedium that stores instructions that, when executed by a processor ofbase station, cause the base station to perform one of methods for(de)activating downlink component carriers in a mobile communicationsystem using component carrier aggregation according to one of thevarious embodiments discussed herein. The execution of the instructionsmay for example cause the base station to transmit on an activeconfigured downlink component carrier an uplink resource assignment to amobile terminal for assigning uplink resources to a mobile terminal,wherein the uplink resource assignment is comprising a bit-maskindicating which of plural configured downlink component carriers are tobe activated, respectively deactivated, and to receive on the assigneduplink resources an acknowledgment for the successful reception of theuplink resource assignment or successful (de)activation of the downlinkcomponent carriers, wherein the acknowledgement is received in form of achannel quality measurement(s) for newly activated downlink componentcarrier(s).

A further embodiment of the invention is providing a computer-readablemedium that stores instructions that, when executed by a processor ofbase station, cause the base station to transmit on an active configureddownlink component carrier a downlink resource assignment to a mobileterminal for assigning downlink resources to the mobile terminal,wherein the uplink resource assignment is indicating which of pluralconfigured downlink component carriers are to be activated, respectivelydeactivated. The instructions further cause the base station to transmitdownlink data to the mobile terminal on the assigned downlink resourcesand within the same sub-frame in which the downlink resource assignmentis transmitted.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE FIGURES

In the following the invention is described in more detail in referenceto the attached figures and drawings. Similar or corresponding detailsin the figures are marked with the same reference numerals.

FIG. 1 shows an exemplary architecture of a 3GPP LTE system,

FIG. 2 shows an exemplary overview of the overall E-UTRAN architectureof 3GPP LTE,

FIG. 3 shows an exemplary sub-frame structure on a downlink componentcarrier as defined for 3GPP LTE (Release 8/9),

FIG. 4 shows an exemplary downlink resource grid of a downlink slot asdefined for 3GPP LTE (Release 8/9),

FIGS. 5 & 6 show the 3GPP LTE-A (Release 10) Layer 2 structure withactivated carrier aggregation for the downlink and uplink, respectively,

FIGS. 7 & 8 show exemplarily linkages between downlink and uplinkcomponent carriers in 3GPP LTE-A (Release 10),

FIGS. 9 & 10 shows the contents of DCI format 0 in 3GPP LTE (Release8/9), respectively 3GPP LTE-A (Release 10) without and with CIF fieldfor cross-carrier scheduling, respectively,

FIG. 11 shows an exemplary improved DCI format 0 for (de)activatingconfigured downlink component carriers for use in 3GPP LTE-A (Release10) and according to an exemplary embodiment of the invention,

FIG. 12 shows another exemplary improved DCI format 0 for (de)activatingconfigured downlink component carriers for use in 3GPP LTE-A (Release10) and according to an exemplary embodiment of the invention,

FIGS. 13 & 14 show a further exemplary improved DCI format 0 for(de)activating configured downlink component carriers for use in 3GPPLTE-A (Release 10) and according to an exemplary embodiment of theinvention, where the interpretation of the content of the DCI format isdepending on the codepoint of the CIF field,

FIG. 15 exemplifies the procedure for the (de)activation of downlinkcomponent carriers in an exemplary 3GPP-based communication systemaccording to an embodiment of the invention,

FIG. 16 exemplifies another procedure for the (de)activation of downlinkcomponent carriers in an exemplary 3GPP-based communication systemaccording to an embodiment of the invention, including PHR reporting andSRS signal activation,

FIGS. 17 & 18 show the contents of DCI format 1 in 3GPP LTE (Release8/9), respectively 3GPP LTE-A (Release 10) without and with CIF fieldfor cross-carrier scheduling, respectively,

FIG. 19 shows an exemplary improved DCI format 1 for (de)activatingconfigured downlink component carriers for use in 3GPP LTE-A (Release10) and according to an exemplary embodiment of the invention, and

FIG. 20 shows another exemplary improved DCI format 1 for (de)activatingconfigured downlink component carriers for use in 3GPP LTE-A (Release10) and according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION

The following paragraphs will describe various embodiments of theinvention. For exemplary purposes only, most of the embodiments areoutlined in relation to an orthogonal single-carrier uplink radio accessscheme according to 3GPP LTE (Release 8) and LTE-A (Release 10) mobilecommunication systems discussed in the Technical Background sectionabove. It should be noted that the invention may be advantageously usedfor example in connection with a mobile communication system such as3GPP LTE (Release 8) and LTE-A (Release 10) communication systemspreviously described, but the invention is not limited to its use inthis particular exemplary communication network.

The explanations given in the Technical Background section above areintended to better understand the mostly 3GPP LTE (Release 8) and LTE-A(Release 10) specific exemplary embodiments described herein and shouldnot be understood as limiting the invention to the described specificimplementations of processes and functions in the mobile communicationnetwork.

As described above, one major drawback of the prior art as known from a3GPP LTE-A (Release 10) system is the necessity to send two PDCCHs inorder to activate a downlink component carrier. The problem in thisprior art solution is that a single downlink PDCCH indicating theactivation of a downlink component carrier cannot simultaneouslyallocate PDSCH resources. Since PDCCH and PDSCH are transmitted in thesame sub-frame in 3GPP LTE, i.e., PDCCH is transmitted for examplewithin the first three OFDM symbols of a sub-frame, and the userequipment is not aware when a downlink component carrier is activated itcannot receive downlink data on the PDSCH within the same sub-frame onthe newly activated downlink component carrier, when an activation PDCCHfor this downlink component carrier is signaled.

The present invention provides a method where a single uplink ordownlink resource assignment is used in order to activate/deactivatedownlink component carriers and further allows simultaneously schedulingof uplink, respectively downlink resources. According to one aspect ofthe invention, a new uplink resource assignment format is proposed thatis allowing the activation/deactivation of individual downlink componentcarriers configured for a mobile terminal (referred to as user equipmentin the 3GPP terminology). The new uplink resource assignment comprisesan indication of the activation state of the configured downlinkcomponent carriers, i.e., indicates which downlink component carrier(s)is/are to be activated or deactivated. Furthermore, in accordance withanother aspect of the invention, a new downlink resource assignmentformat is proposed that is allowing the activation/deactivation ofindividual downlink component carriers configured for a mobile terminaland the simultaneous assignment of downlink resources for thetransmission of downlink data to the mobile terminal. The new downlinkresource assignment comprises an indication of the activation state ofthe configured downlink component carriers, i.e., indicates whichdownlink component carrier(s) is/are to be activated or deactivated.

This indication in both resource assignments may be sent for allconfigured component carriers, or for all configured component carriersother than the one downlink component carrier which needs to be alwaysactivate for a user equipment in RRC connected mode (this componentcarrier is referred to as the anchor carrier of the user equipment).

Moreover, the indication of the activation state is for exampleimplemented by means of a bit-mask that indicates which of theconfigured downlink component carriers are to be activated respectivelydeactivated.

Alternatively, if the proposed resource assignment for uplink,respectively downlink should only activate or deactivate one singleconfigured downlink component carrier, the indication would need toindicate at least an identifier of the configured downlink componentcarrier to be (de)activated. The indication of the identifier of theconfigured downlink component carrier would then cause the mobileterminal to toggle the activation state of the indicated downlinkcomponent carrier (configured but deactivated ⇄ active). For signalingthe component carrier ID, there would be ┌log₂(N−1)┐ bits required,given that the anchor carrier cannot be activated/deactivated by theuplink resource assignment, where N is the number of configuredcomponent carriers and ┌x┐ is the ceiling function.

As an implicit indication of the activation state may lead to ade-synchronization of the activation states in the mobile terminal andthe access network (base station), it may be advantage to include afurther additional bit/flag to the uplink resource assignment that isexplicitly indicating the activation state (configured but deactivatedor active) for the indicated downlink component carrier.

Another alternative possibility to signal the activation state of theconfigured downlink component carriers would be the use of a singlebit/flag that indicates the activation state (configured but deactivatedor active) of all downlink component carriers other than the onedownlink component carrier which is always active, e.g., the “special”or anchor component carrier in the downlink. This would only allow thesimultaneous activation or deactivation of all non-anchor componentcarriers, but would significantly reduce the signaling overhead.

Considering the use of this new uplink, respectively downlink resourceassignment format in a 3GPP based communication system using carrieraggregation in the downlink, such as 3GPP LTE-A (Release 10) or futurereleases using carrier aggregation, the new resource assignment formatmay be considered an extension to existing DCI formats, or a new DCIformat.

In one exemplary embodiment of the invention, the DCI format of theuplink, respectively downlink resource assignment has the same size asat least one other DCI format defined in the communication system.Furthermore, in a 3GPP based communication system using OFDM on thedownlink, it can be assumed that the resource assignment is forming thepayload (DCI) of a PDCCH transmitted within a sub-frame on a downlinkcomponent carrier to one or more user equipments and the user equipmentsperform a blind decoding on the different DCI formats signaled in asub-frame on PDCCH. Using the same size as at least one other DCI formatdefined in the communication system for the resource assignment format,and using an implicit or explicit indication of this format (as will beexplained below in further detail) it is possible not to increase theblind decoding efforts of a mobile terminal.

If using a bit-mask to indicate the activation state of the downlinkcomponent carriers configured for a given mobile terminal, each of thebits in the bit-mask is for example associated to a respectiveconfigured downlink component carrier of plural configured downlinkcomponent carriers, and indicates its activation state. By checking thisbit-mask comprised in the uplink, respectively downlink resourceassignment, the mobile terminal can determine for each of the configureddownlink component carriers, whether the activation state of therespective downlink component carrier is changed, i.e., which one orones of the configured downlink component carriers need to be activatedor deactivated.

In one exemplary embodiment and implementation of the invention, adownlink component carrier could be defined to be in one of thefollowing three activation states: non-configured, configured butdeactivated and active. When a downlink component carrier is configuredbut deactivated, the user equipment does not need to receive thecorresponding PDCCH or PDSCH, nor is it required to perform CQImeasurements. Conversely, when a downlink component carrier is active,the user equipment shall receive PDSCH and PDCCH (if present), and isexpected to be able to perform CQI measurements. After configuration ofcomponent carrier(s) same is/are in configured but deactivated state. Inorder to enable PDCCH and PDSCH reception on a downlink componentcarrier, the downlink component carrier needs to be transitioned fromconfigured but deactivated state to active state. The new proposeduplink, respectively downlink resource assignment may for example beused for indicating state transitions between configured but deactivatedand active (“configured and activated”). If using a bit-mask for thispurpose, the logical value 1 of a bit of the bit-mask may indicate theconfigured downlink component carrier associated to the bit beingactive, while the logical value 0 of a bit of the bit-mask may indicatethe corresponding configured downlink component carrier associated tothe bit being configured but deactivated (or vice versa).

Since the proposed uplink/downlink resource assignment is received onone of the configured downlink component carrier, this implies that thisdownlink component carrier is in active state. For example, the downlinkcomponent carrier on which the uplink/downlink resource assignment isreceived may be (always) a designated “special” component carrier (oranchor component carrier) that is always configured and activated forthe mobile terminal. Hence, the uplink resource assignment does not needto (but may) include an indication of the activation state for thisspecial component carrier.

If also an indication of the activation state for the special componentcarrier is signaled, and irrespective of whether the proposed newuplink/downlink resource assignment is signaled on the special componentcarrier or another configured component carrier, it may be for examplepossible to reconfigure the special component carrier by means of thenew uplink /downlink resource assignment discussed herein.

Furthermore, in a more advanced exemplary implementation, the uplinkresource assignment including the component carrieractivation/deactivation information may also instruct the mobileterminal to send a channel quality measurement for the newly activatedcomponent carriers (i.e., those component carrier(s) for which the statehas changed from deactivated to activated). Accordingly, the mobileterminal performs a channel quality measurement for each activatedcomponent carrier and sends the result of the measurement to the basestation (referred to as eNodeB in the 3GPP terminology) on the uplinkresources that have been assigned to the mobile terminal by means of theuplink resource assignment. The channel quality measurement results maybe for example signaled in form of CQI information.

The transmission of the channel quality measurement result(s) indicatesto the base station that the mobile terminal has successfully receivedthe uplink resource assignment, respectively, has successfullyactivated/deactivated the configured downlink component carriers. Hence,the transmission of the channel quality measurement result(s) can beconsidered an acknowledgment of the uplink resource assignment,respectively the activation/ deactivation of configured downlinkcomponent carriers by the mobile terminal.

Another aspect of the invention is related to the distinction of the newproposed uplink/downlink resource assignments from an “ordinary”uplink/downlink resource assignment, in particular when assuming thatthe mobile terminals perform a blind decoding of the downlink controlchannel information (DCI formats). Hence, the format of the new proposedresource assignments may need to be distinguished from other DCIformats. One possibility is to define a new DCI format (of a new givensize) for the resource assignments proposed herein. This may howeverimply an increase in the blind decoding attempts that need to beperformed by the mobile terminal in order to decode the new DCI format.An alternative implementation according to a further embodiment of theinvention is to reuse existing DCI formats for signaling anuplink/downlink resource assignment and to provide the distinction ofthe different uplink resource assignment formats by using unusedcodepoints in some field(s) of the reused existing DCI format or bymeans of masking the CRC attachment with a newly defined RNTI definedper mobile terminal for component carrier (de)activation.

For example, when implementing the invention in a 3GPP-based system likeLTE-A (Release 10) or its successors, the uplink DCI format 0 as definedfor 3GPP LTE (Release 8/9) or the downlink DCI format 1A as defined for3GPP LTE (Release 8/9), could be reused for (de)activation of downlinkcomponent carrier(s). If an uplink/downlink resource assignment that is(de)activating downlink component carrier(s) is signaled, its CRC may befor example scrambled with a new user equipment-specific RNTI definedfor this purpose, referred to as CC-RNTI in the following. The CC-RNTImay be for example allocated to a user equipment when the eNodeBconfigures the set of uplink/downlink component carrier(s). The CC-RNTImay be for example signaled to a user equipment in a RRC ConnectionReconfiguration message which includes the set of downlink/uplinkcomponent carriers(s) to be aggregated. Hence, by detecting at the userequipment that the CRC attachment of the payload of the PDCCH (i.e., theresource assignment in this case) is masked by the CC-RNTI, the userequipment could thus conclude on the format of the payload of the PDCCHand appropriately read the different fields of the uplink resourceassignment including information on the (de)activation of configureddownlink component carrier(s).

According to another alternative embodiment of the invention, a CIFfield (if present) in the uplink/downlink resource assignment may beused in order to indicate the format of the payload of the PDCCH, i.e.,whether the payload is a normal uplink/downlink resource assignment or auplink resource assignment including information on the (de)activationof configured downlink component carrier(s). As described in thetechnical background section, the CIF (carrier indicator field) iscomprised of three bits and identifies the component carrier for whichthe specific control signaling information is intended, i.e., incross-carrier scheduling scenarios. Since three bits offer 8 codepoints,but there could be at most 5 downlink/uplink components configured foran user equipment, some of the CIF codepoints are unused, i.e.,codepoints 6, 7 and 8. According to this embodiment, at least one ofthose unused codepoints of the CIF field is used to indicate that theuplink /downlink resource assignment comprises information on the(de)activation of downlink component carrier(s) and the user equipmentwill know how to interpret certain bits in the payload of the PDCCH. Asthe DCI formats for normal uplink/downlink resource assignments (withoutinformation on the (de)activation of configured downlink componentcarrier(s)) and uplink/downlink resource assignments with information onthe (de)activation of configured downlink component carrier(s) aredistinguished by the codepoint signaled in the CIF field, the same RNTIas used for uplink grants (C-RNTI) can be used to scramble the CRC.Hence, no additional new CC-RNTI would need to be defined in thisalternative embodiment.

Furthermore, in another embodiment of the invention, the twopossibilities how to indicate the DCI format of the PDCCH payloaddescribed above may be used together. As mentioned in the technicalbackground section, in 3GPP LTE-A (Release 10) the presence of CIF in anuplink PDCCH is configurable. Therefore, user equipments that areconfigured to include CIF in the PDCCH payload, the eNodeB uses thepredefined CIF codepoint(s) to indicate that PDCCH payload is a resourceassignment with information on the (de)activation of configured downlinkcomponent carrier(s). User equipments that are configured to not includeCIF in the PDCCH payload will be assigned the CC-RNTI discussed above,which is then used by the eNodeB to distinguish resource assignmentswith information on the (de)activation of configured downlink componentcarrier(s) from normal resource assignments (without information on the(de)activation of configured downlink component carrier(s)).

As outlined above, the introduction of a CC-RNTI or the reservation ofat least one CIF codepoint allows the redefinition of some of the DCIfields to incorporate the indication of the downlink componentcarrier(s) to be (de)activated. Exemplarily assuming that there is amaximum of N=5 configured downlink component carriers, and that there isno activation state to be signaled for the specific downlink componentcarrier which is always active, e.g., the anchor carrier, N−1=4 bits areneeded in order to have the possibility to activate/deactivate anycombination of downlink component carriers using a bit-mask. Each bit inthe bit-mask thereby represents the activation state of one of thedownlink component carriers. For example, a bit within the bit-mask setto “1” may indicate that the corresponding downlink component carriershould be activated; a bit set to “0” indicates that the correspondingdownlink component carrier should be deactivated (or vice versa).

In one exemplary embodiment of the invention, one of DCI formats alreadyexisting in the respective system where the invention is implemented isredefined in order to encompass the signaling of the bit-mask toindicate the (de)activation of the configured downlink componentcarrier(s). With respect to the implementation of the proposed uplinkresource assignment, and if reusing an uplink DCI format 0 alreadydefined in 3GPP LTE (Release 8/9) or 3GPP LTE-A (Release 10), 4 bitsneed to be redefined in this DCI format in order to be able to signalwithin the bit-mask (assuming that there is a maximum of N=5 configureddownlink component carriers). FIG. 9 shows the DCI format 0 for FDD in3GPP LTE (Release 8/9). The DCI format 0 consists of:

-   -   a format flag (Flag Format 0/1A) for distinguishing DCI Format 0        and DCI format 1A, which are defined to have the same number of        bits/size,    -   a hopping flag (Hopping Flag) indicating whether or not the user        equipment should employ uplink resource hopping,    -   a resource block assignment field assigning uplink resources on        the PUSCH to the user equipment (when triggering aperiodic        channel quality feedback, the channel quality feedback and        optionally further user data is multiplexed and transmitted on        these assigned resources via that PUSCH),    -   a modulation and coding scheme field (MCS&RV) that is indicating        the modulation scheme, coding rate and the redundancy version        for the transmission on the assigned resources on the PUSCH,    -   a new data indicator (NDI) to indicate whether the user        equipment has to send new data or a retransmission,    -   a DMRS field (Cyclic Shift DMRS) for configuring the cyclic        shift applied to the reference symbol sequence,    -   a CQI request flag for triggering an aperiodic channel quality        feedback report from the user equipment, and    -   if required one or more padding bit(s) to align the size of the        dedicated control information to a predetermined number of bits.

Furthermore, as shown in FIG. 10 the extended DCI format 0 in 3GPP LTE-A(Release 10) is essentially similar to the DCI format 0 of 3GPP LTE(Release 8/9), except for further including the CIF field for indicatingthe uplink component carrier to which the signaled resource assignmentpertains in cross-scheduling scenarios.

Under the assumption that the uplink transmission which is scheduled bythe uplink resource assignment including the information on the(de)activation of downlink component carrier(s), implies a new initialtransmission, the NDI bit, which usually indicatesinitial/retransmission, can be reused. Similarly the “CQI request” flagcould be reused since it could be defined by rule, that the userequipment has always to transmit an aperiodic CQI when downlinkcomponent carrier(s) are activated. The remaining two bits which arerequired for the signaling of the 4-bit bitmask may for example stolenfrom the TPC bits, since there are not necessarily required for thetransmission of the aperiodic CQI: Robustness of the uplink transmissionmay also be achieved by properly choosing a conservative modulation andcoding scheme, so that no further power control may be required.

Hence, the user equipment could interpret the content of the decodeddownlink control channel information obtained from the PDCCH dependingon which RNTI has been used to scramble the CRC code of the CRCattachment. If the CC-RNTI has been used by the base station to mask theCRC of the uplink resource assignment, the user equipment will interpretthe NDI flag, the TPC field and the CQI flag of DCI format 0 as a 4-bitbit-mask that indicates which of the configured downlink componentcarrier(s) is/are to be (de)activated. FIG. 11 shows an exemplaryimproved DCI format 0 for (de)activating configured downlink componentcarriers for use in 3GPP LTE-A (Release 10) and according to anexemplary embodiment of the invention, where the NDI flag, the TPC fieldand the CQI flag are interpreted as a bit-mask, in case the CC-RNTI hasbeen used to scramble the CRC. If the CRC in the CRC attachment has beenmasked with the C-RNTI, the user equipment interprets the fields of DCIformat 0 as defined for 3GPP LTE (Release 8/9) and as shown in FIG. 9—i.e., as a “normal” uplink resource assignment.

FIG. 12 shows another exemplary improved DCI format 0 for (de)activatingconfigured downlink component carriers for use in 3GPP LTE-A (Release10) and according to an exemplary embodiment of the invention. In thisexample, a new DCI format is defined which is based on the DCI format 0known from 3GPP LTE (Release 8/9). As for the example of FIG. 11, it canbe ensured that the size of the format is similar to DCI format 0 and1A, so that no further blind decoding attempt is needed by the userequipment to decode this new DCI format. In the exemplary DCI formatshown in FIG. 12, a new DL CC (de)activation field is defined, which isconsisting of 4 bits to convey the bit-mask. As outlined above inconnection with FIG. 11, the NDI flag, the TPC field and the CQI flagare omitted in the uplink resource assignment of FIG. 12 to accommodatethe DL CC (de)activation field.

Although the exemplary embodiments described above have been explainedin connection with reusing the DCI format 0 of 3GPP LTE (Release 8/9),it is likewise possible to reuse DCI format 0 of 3GPP LTE-A (Release10). In the latter case, the DCI format reuse or the new DCI format ofthe uplink resource assignment the for (de)activating configureddownlink component carriers would look like the examples in FIG. 11 andFIG. 12, except for additionally including a CIF field.

Please also note that the reuse of the NDI flag, the TPC field and theCQI flag is just one example for reusing the fields of the DCI format 0of 3GPP LTE (Release 8/9) and LTE-A (Release 10). Another option is toreuse the Flag Format 0/1A, the TPC field and the CQI flag oralternatively Flag Format 0/1A, the TPC field and NDI flag to free 4bits that can be used to signal the bit-mask for (de)activating downlinkcomponent carrier(s). If the CC-RNTI is used for indicating the DCIformat, the Flag Format 0/lA would no longer be needed in the DCI formatand could therefore be reused.

Alternatively assuming that the uplink transmission scheduled by theuplink resource assignment should be robust, a modulation schemeyielding high spectral efficiency (such as 64-QAM) would likely not beused for the transmission required. This would allow using only 4 out ofthe 5 bits for the MCS field for the signaling of the modulation andcoding scheme, so that “only” 2⁴=16 MCS levels could be signaled. The“freed” 1 bit of the MCS field could also be used as one bit of thebit-mask. This would for example allow reusing the Flag Format 0/1A, theNDI flag, 1 bit of the MCS field and the CQI flag for the signaling ofthe 4-bit bit-mask. This way, the TPC commands may still be signaledthereby further improving control of the reliability of the uplinktransmission.

Hence, the bit-mask for signaling the activation state of the downlinkcomponent carriers may thus be formed by an arbitrary combination of thefollowing fields of DCI format 0 of 3GPP LTE (Release 8/9) or 3GPP LTE-A(Release 10):

-   -   Flag Format 0/1A (1 bit),    -   1 bit of the MCS field,    -   NDI flag (1 bit),    -   TPC command field (2 bits), and    -   CQI request flag (1 bit),        that yields 4 bits for signaling of the bit-mask.

Alternatively, as mentioned previously, if the uplink resourceassignment should only activate or deactivate one single configureddownlink component carrier, the indication would need to indicate atleast an identifier of the configured downlink component carrier to be(de)activated. The indication of the identifier of the configureddownlink component carrier would then cause the mobile terminal totoggle the activation state of the indicated downlink component carrier(configured but deactivated ⇄ active). For signaling the componentcarrier ID, there would be ┌log₂(N−1)┐ bits required, given that theanchor carrier cannot be activated/deactivated by the uplink resourceassignment. For the case of N=5 this would mean that 2 bits would berequired to signal the indication of the configured downlink componentcarrier to be (de)activated, respective 3 bits would be required tosignal the indication of the configured downlink component carrier to be(de)activated and an explicit indication of the activation state.

According to another embodiment, DL CC (de)activation field forsignaling the activation state of the one downlink component carrier maythus be formed by an arbitrary combination of the following fields ofDCI format 0 of 3GPP LTE (Release 8/9) or 3GPP LTE-A (Release 10):

-   -   Flag Format 0/lA (1 bit),    -   1 bit of the MCS field,    -   NDI flag (1 bit),    -   TPC command field (2 bits), and    -   CQI request flag (1 bit),        that yields 2 bits (respectively 3) bits for signaling an        identifier the one downlink component carrier to be        (de)activated (and the explicit indication of the activation        state). One exemplary implementation to obtain 3 bits for        signaling an identifier the one downlink component carrier to be        (de)activated and the explicit indication of the activation        state would be the combination Flag Format 0/1A, NDI flag and        CQI request flag. Similarly, also the TPC command field and one        of the Flag Format 0/1A, NDI flag and CQI request flag could be        used.

In another exemplary embodiment, the activation state of the configureddownlink component carriers is signaled by a single bit/flag thatindicates the activation state (configured but deactivated or active) ofall downlink component carriers other than the one downlink componentcarrier which is always active, e.g., the “special” or anchor componentcarrier in the downlink. This allows only a simultaneous activation ordeactivation of all non-anchor component carriers, but wouldsignificantly reduce the signaling overhead. For signaling this singlebit/(de)activation flag one of the following flags:

-   -   Flag Format 0/1A (1 bit),    -   1 bit of the MCS field,    -   NDI flag (1 bit),    -   TPC command field (2 bits),    -   CQI request flag (1 bit)        of DCI format 0 of 3GPP LTE (Release 8/9) or 3GPP LTE-A        (Release 10) may be reused.

As to the implementation of the downlink resource assignment enablingthe signaling of the activation state of downlink component carriers inthe 3GPP context, another embodiment of the invention proposes the reuseor redefinition of downlink DCI format 1A of 3GPP LTE (Release 8/9) or3GPP LTE-A (Release 10).

The downlink DCI format 1A for FDD mode of 3GPP LTE (Release 8/9) isshown in FIG. 17 and consists of:

-   -   a format flag (Flag Format 0/1A) for distinguishing DCI Format 0        and DCI format 1A, which are defined to have the same number of        bits/size    -   Localized/Distributed assignment flag—indicating whether the        localized or distributed transmission mode is used    -   Resource Block Assignment (RBA) field for assigning downlink        resources (resource blocks) on the PDSCH to the user equipment        according to the given resource allocation type. The number of        bits required for the RBA field depends on the allocation type        (RA field) and bandwidth of the assigned component carrier.    -   modulation and coding scheme field (MCS) that is indicating the        modulation scheme, coding rate and the redundancy version for        the transmission on the assigned resources on the PDSCH    -   HARQ process number indicating the HARQ process to be used for        the downlink transmission on the assigned resources    -   new data indicator (NDI) flag for indicating that the        transmission on the given HARQ process is a new protocol data        unit (PDU)    -   redundancy version (RV) field for indicating the redundancy        version of the downlink transmission on the assigned resources    -   transmission power control (TPC) command field for transmission        of control information on the PUCCH

Downlink DCI format 1A of 3GPP LTE-A (Release 10) is shown in FIG. 18and comprises in addition to the fields of downlink DCI format 1 of 3GPPLTE (Release 8/9) the a carrier indicator field (CIF) for indicating onwhich of the component carriers the resources are assigned. For TDDmode, the DCI formats 1A of 3GPP LTE (Release 8/9) and 3GPP LTE-A(Release 10) further comprise a Downlink Assignment Index.

According to another embodiment of the invention, the NDI bit of DCIformat 1A is reused to provide a flag (DL CC (de)activation flag) thatallows the eNodeB to activate or deactivate all downlink componentcarriers other than the always active downlink component carrier. Anexample of a new DCI format for the downlink resource assignmentcomprising the DL CC (de)activation flag is shown in FIG. 19. In anotheralternative embodiment of the invention, the TPC command for PUCCH fieldof DCI format 1A or NDI flag and TPC command for PUCCH field are reusedand form a DL CC (de)activation field. An exemplary DCI format for thedownlink resource assignment is shown in FIG. 20.

Please note that the DCI format in the examples of FIG. 19 and FIG. 20may further include a CIF field as shown in FIG. 18. In case the NDIflag of the DCI format 1A is reused, it may be desirable to define thatthe downlink transmission (transport block) to the user equipment on theallocated downlink resources is always an initial transmission, when theproposed downlink resource assignment including the DL CC (de)activationflag is received. Furthermore, the user equipment may also assume aknown NDI value for the HARQ process that is providing the downlinktransmission.

It should be noted that in all alternatives described above, a reuse offields of the DCI format and interpretation of the content depending onthe RNTI used for the masking of the CRC could be used (as explained inconnection with FIG. 11) or the resulting contents of the DCI field canbe defined as a new DCI format (as explained in connection with FIGS.12, 19 and 20).

In the examples on how to signal an indication of the downlink componentcarrier(s) to be activated or deactivated discussed in the paragraphsabove, it has been assumed that the base station assigns a special RNTI(CC-RNTI) to the user equipments for signaling information related tothe activation and deactivation of the downlink component carriersconfigured by a respective user equipment. Based on the use of theCC-RNTI, the user equipments can determine how the DCI format of theuplink/downlink resource assignment received on the PDCCH needs to beinterpreted, respectively, which fields are contained therein.

In another alternative implementation according to another embodiment ofthe invention, the eNodeB uses one of one or more predefined CIFcodepoints to indicate that PDCCH payload is an uplink/downlink resourceassignment with information on the (de)activation of configured downlinkcomponent carrier(s), so that no special RNTI would be needed. The userequipment thus decodes the PDCCH and determines the DCI format(respectively the content/interpretation of the remaining fields in theDCI format) depending on the codepoint signaled in the CIF field. Inthis case the assigned uplink/downlink resources indicated by the PDCCHis intended for either a predefined uplink/downlink component carrier orfor the uplink/downlink component carrier that would be used for thecase of non cross-carrier scheduling, i.e., if no CIF field was present.This may be for example the uplink/downlink anchor component carrier ofthe mobile terminal.

FIGS. 13 and FIG. 14 show an exemplary improved uplink DCI format 0 for(de)activating configured downlink component carriers for use in 3GPPLTE-A (Release 10) and according to this embodiment of the invention,where the interpretation of the content of the DCI format is dependingon the codepoint of the CIF field. If the codepoint of the CIF field is“111”, the DCI format (uplink resource assignment) comprises a DL CC(de)activation field for signaling the activation state of the downlinkcomponent carriers (see FIG. 13), while in case the codepoint is not“111”, the DCI format is the DCI format 0 as shown in FIG. 10, and theCIF field indicate the cross-scheduled component carrier on which theuplink resources are assigned. Please note that the definition ofspecial CIF codepoint(s) for indicating the DCI format is of course alsoapplicable to the DCI format as shown in FIG. 19 and FIG. 20 for thedownlink assignment case, assuming that a CIF field is added to theformats.

In another alternative implementation according to another embodiment ofthe invention, two predefined CIF codepoints are used for indicationthat the DCI format (resource assignment) comprises informationidentifying at least one DL component carrier which is to be activatedrespectively deactivated. If the codepoint of the CIF field is “111”,the DCI format (resource assignment) indicates the activation of the atleast one downlink component carrier identified by the identifier field,whereas when if the codepoint of the CIF field is “110” the DCI formatindicates the deactivation of the at least one downlink componentcarrier identified by the identifier field in the DCI format.

Furthermore another aspect of the invention relates to the transmissionof the aperiodic CQI in response to a downlink component carrier (de)activation. As explained above, in one example implementation, theactivation of a downlink component carrier (transition from configuredbut deactivated state to active state) by means of an uplink resourceassignment, causes the mobile terminal to perform a channel qualitymeasurement for each of the newly activated component carrier and tosignal the results of the measurement to the base station. Since it maynot always be required or beneficial for the base station to receive CQIinformation when (de)activating downlink component carriers, it may bedesirable for the base station to have the possibility to enable/disablethe transmission of the channel quality measurements. In implementationswhere the CQI request flag is not used for signaling the indication ofthe activation status of the downlink component carriers, the CQIrequest flag could be used by the base station to control thetransmission of CQI information for the newly activated downlinkcomponent carriers.

For cases where the CQI request flag is used for signaling theindication of the activation status of the downlink component carriers,according to one embodiment of the invention, it is proposed to controlthe transmission of channel quality feedback/CQI by setting thecodepoint signaled in the Resource Block assignment (RBA) field. Forexample setting the RBA field to all “1”s, which is an invalid resourceallocation, the base station may disable the channel qualityfeedback/CQI reporting. The user equipment would still (de)activate thedownlink component carrier(s) as signaled, however without transmittingchannel quality feedback/CQI information for the newly activatedcomponent carriers.

Another possibility to suppress channel quality reporting is related tothe use of the CIF flag for distinguishing the uplink resourceassignment formats (as explained in connection with FIG. 13 and FIG. 14above). Since more that one CIF codepoint may not be needed, twocodepoints may be reserved to indicate the format of the uplink resourceassignment. One of these two codepoints could be defined to indicate theuplink resource assignment comprising information on the (de)activationof downlink component carrier(s) and requests the mobile terminal toreport channel quality on the newly activated downlink componentcarriers, while the other of the two codepoints could be defined toindicate the uplink resource assignment comprising information on the(de)activation of downlink component carrier(s) and requests the mobileterminal not to report channel quality on the newly activated downlinkcomponent carriers.

In order to provide sufficient robustness for the downlink componentcarrier (de)activation signaling, it is proposed in another embodimentof the invention that a transmission on the uplink resources allocatedby the uplink resource assignment (comprising the information on thedownlink component carrier (de)activation) serves as an acknowledgementfor the reception of the uplink resource assignment. Hence, if thechannel quality is reported on the assigned uplink resources, uponreception of this channel quality information at the base station, samecan assume that the uplink resource assignment (comprising theinformation on the downlink component carrier (de)activation) wascorrectly received by the mobile terminal.

FIG. 15 exemplifies the procedure for the (de)activation of downlinkcomponent carriers in an exemplary 3GPP-based communication systemaccording to an embodiment of the invention. It is exemplarily assumedthat there are two downlink component carriers (DL CC1 and DL CC2) andone uplink component carrier (UL CC1) configured for carrieraggregation. First, DL CC2 is deactivated and only DL CC1 and UL CC1 areactive (UL CC1 and DL CC1 are always active, since the user equipmentsneeds to always have at least one active uplink and downlink componentcarrier in RRC connected mode).

At time T1, e.g., when DL traffic demand increases, the eNodeB activatesDL CC2 for the user equipment by sending an uplink resource assignment(UL PDCCH) scrambled with CC-RNTI which initiates the activation of DLCC2. Upon reception of the uplink resource assignment at the userequipment, the user equipment activates DL CC2, e.g., start monitoringfor corresponding PDCCH/PDSCH, and measures channel quality (CQIinformation) for DL CC2. The format of the CQI could be for examplepreconfigured by eNodeB, so that the user equipment is aware whether itshould report a wide-band CQI or a frequency-selective CQI. The userequipment transmits at time T2 the calculated CQI information on thePUSCH resource assigned on the uplink (UL CC1) by the uplink resourceassignment received at time T1. The CQI information is transmitted 4 msafter reception of the uplink resource assignment received at time Ti,similar to the implementation foreseen in 3GPP LTE (Release 8/9).

After some number of sub-frames in which eNodeB transmitted downlinkdata on both activated downlink component carriers DL CC1 and DL CC2,the eNodeB decides to deactivate DL CC2. Accordingly, the eNodeB sendsat time T3 another uplink resource assignment (UL PDCCH) scrambled withCC-RNTI and corresponding bit-mask that indicates the deactivation of DLCC2. Since CQI information for a deactivated downlink component carriermay not be useful, the eNodeB may sets the RBA field to all “1”s, inorder to disable CQI transmission.

It should be also noted that since an the uplink resource assignments attimes T1 and T3 are used for the activation, respectively deactivationof downlink component carrier DL CC2, the eNodeB can simultaneously(de)activate the downlink component carrier and transmit downlink dataon the anchor carrier, i.e., DL CC1.

According to some embodiments discussed above, channel quality feedbackhas been provided by means of CQI information, i.e., aperiodic CQI, inthe uplink on the PUSCH resources assigned by the uplink resourceassignment activating downlink component carrier(s). In a furtherembodiment, in addition to the channel quality information reported forthe newly activated downlink component carrier(s), the mobile terminalmay optionally further transmit sounding reference signal(s) (SRS) onthe uplink component carrier(s) which are linked to the activateddownlink component carrier(s) and/or Power Headroom Report (PHR)information for the uplink component carrier(s) which are linked to thenewly activated downlink component carrier(s). The PHR information issent on the uplink resources assigned by the uplink resource assignment.The SRS and PHR information is for example useful for eNodeB in order toefficiently schedule PUSCH transmissions.

Therefore, according to this embodiment of the invention, the basestation may also schedule PHR transmissions and/or SRS when activatingdownlink component carrier(s). Hence, instead of or in addition toreporting the channel quality of activated downlink component carrierson the uplink resources that have been assigned by the new proposedplink resource assignment, the mobile terminal may also signalscheduling related information to the base station such as SRS and/orPHR reports.

In the exemplary scenario shown in FIG. 16, the power headroominformation for UL CC2 is transmitted on UL CC1. Since there is nouplink resource assignment on UL CC2 for the sub-frame in which the userequipment should calculate the power headroom for UL CC2, according to afurther aspect and embodiment of the invention, the calculation of thepower headroom for UL CC2 is redefined in comparison to 3GPP LTE(Release 8/9). In 3GPP LTE (Release 8/9) a power headroom report canonly be sent in sub-frames where user equipment has an uplink assignmentfor transmission on the PUSCH (transport block), since the powerheadroom indicates the difference between the nominal user equipment'smaximum transmit power and the estimated power for the assigned uplinktransmission on the PUSCH. For the case there is no uplink assignment onan uplink component carrier for which a power headroom is to bereported, it is therefore proposed that the power headroom for theuplink component carrier which has no uplink resource assignment for thesub-frame in which power headroom should be determined is calculated byusing a preconfigured reference uplink resource allocation. Essentially,the power headroom is then indicating in the difference between thenominal user equipment's maximum transmit power and the estimated powerfor the uplink transmission according to the preconfigured referenceuplink resource allocation. The preconfigured reference uplink resourceallocation may be for example signaled to the user equipment by radioresource control (RRC) signaling.

Similarly as for the channel quality reporting, also the transmission ofSRS respectively PHR is not in all cases beneficial/required. Thereforesimilar to the embodiments described above, the base station may alsoenables/disables SRS and/or PHR reporting when activating ordeactivating downlink component carrier(s). This could be achieved bysimilar mechanisms explained above for the suppression of channelquality feedback. Hence, including a special flag to the uplink resourceassignment or defining special codepoints in the CIF field or RBA fieldof the uplink resource assignment could be used to indicate to themobile terminal whether it is required to send SRS and/or PHR reports.

Alternatively, a predetermined rule could define whether SRS/PHRinformation should be transmitted. For example, the mobile terminal onlysends SRS on the linked uplink component carrier and/or send PHRinformation for the linked uplink component carrier(s), in case thelinked uplink component(s) are not yet active, i.e., no PUSCH/PUCCHtransmissions were made by the mobile terminal on the linked uplinkcomponent carrier(s).

Considering the scenario shown in FIG. 8 as a configuration example of auser equipment, the transmission of SRS/PHR for the downlink componentcarrier activation case will be highlighted in the following withrespect to FIG. 16. The assumption is that only DL CC1 and UL CC1 arecurrently activated and the eNodeB decides to also activate DL CC2 andDL CC3 at time T1. The eNodeB signals the proposed uplink resourceassignment to the user equipment indicating to activate those DL CC2 andDL CC3. Furthermore the uplink resource assignment orders the userequipment to also send PHR information for the uplink componentcarrier(s) linked to the new activated downlink componentcarrier(s)—i.e., UL CC1 and UL CC2 in this example—and to transmit SRSon the linked uplink component carriers(s).

Upon the reception of the new proposed uplink resource assignment theuser equipment's behavior according to one embodiment of the inventionwould be the following: The user equipment activates DL CC2 and DL CC3.Furthermore, the user equipment will measure CQI information on the twonewly activated DL CCs and sends at time T2 the CQI reports for DL CC2and DL CC3 on the uplink resources on UL CC1 assigned by the uplinkresource assignment. Additionally, the user equipment will send powerheadroom information for UL CC2 on the assigned resources on UL CC1, asthe activated DL CC3 is linked UL CC2. Moreover, user equipment willstart transmitting SRS on UL CC2.

According to a further embodiment of the invention, the configurationparameters for the SRS transmission are signaled to the user equipmentvia higher layer signaling, i.e., RRC signaling. For example whenconfiguring the user equipment with the set of downlink and uplinkcomponent carrier(s) for carrier aggregation, the configuration messagemay also include the SRS configuration parameters for a specific uplinkcomponent carrier. Those configuration parameters may for exampleinclude the sub-frame configuration, i.e., set of sub-frames in whichSRS may be transmitted within a radio frame, a periodicity and soundingbandwidth. Similarly also the configuration related to channel qualitymeasurements on a downlink component carrier, i.e., transmission modeand reporting mode may be signaled within the component carrierconfiguration message.

Another embodiment of the invention relates to an improved deactivationmechanism for the downlink component carriers in a 3GPP-basedcommunication system, e.g., 3GPP LTE-A (Release 10). As outlined above,it may not be always required/beneficial when user equipment reports CQIinformation in response to a deactivation of a component carrier. Forexample, for the deactivation case there does not seem to be a goodmotivation to send CQI information for a downlink component carrierwhich has just been deactivated. Therefore the uplink resourceallocation related field in the uplink resource assignment, i.e., RBAfield, MCS filed, UL hopping flag, and the DMRS field could be used forsome other purpose.

When user equipment monitors the PDCCH, there is always a certainprobability (false alarm rate) that the mobile terminal falsely detectsa PDCCH: the CRC check of the PDCCH may be correct even though the PDCCHwas not intended for this user equipment, i.e., CRC passes even thoughthere is a RNTI mismatch (unintended user). This so called false alarmmight happen, if the two effects of transmission errors caused by theradio channel and RNTI mismatch cancel each other. The probability of afalsely positive decoded PDCCH depends on the CRC length. The longer theCRC length, the lower the probability that a CRC-protected message isfalsely correct decoded. With the CRC size of 16 bit the false alarmprobability would be 1.5·10⁻⁵.

In case a user equipment falsely detects a PDCCH with an uplink resourceassignment indicating the deactivation of certain downlink componentcarrier(s) the user equipment would stop monitoring PDCCH/PDSCH forthose indicated downlink component carrier(s) and also stops reportingCQI measurements. Given the severe consequences of such user equipmentbehavior, it is therefore desirable to decrease the false alarmprobability. One mean to lower the false alarm rate to an acceptablelevel proposed in this embodiment is to use a “Virtual CRC” in order toexpand the 16-bit CRC. That is, the length of CRC field can be virtuallyextended by setting fixed and known values to one or more of the DCIfields of the uplink resource assignment signaled on the PDCCH that arenot useful for downlink component carrier deactivation, such as RBAfield, MCS filed, UL hopping flag, and the DMRS field. The userequipments shall ignore the PDCCH comprising the uplink resourceassignment for downlink carrier deactivation, if the values in thesefields are not correct (i.e., are not corresponding to the knownvalues). Since uplink resource allocation related DCI fields areessentially not required for the case of downlink component carrierdeactivation, those fields could be used to extend the CRC virtually andthereby decreasing the false alarm probability. Similar mechanism forextending the CRC length virtually in order to further decrease thefalse alarm rate as described may be also applied for the DL componentcarrier activation case.

Another aspect of the invention is related to the HARQ protocoloperation for the HARQ process used for transmitting the uplink resourceassignment for (de)activation of downlink component carrier(s). Itshould be noted that this applies only to the case where there is atransmission (transport block) on the uplink shared channel (UL-SCH)scheduled by the uplink resource assignment indicating a downlinkcomponent carrier (de)activation, e.g., PHR information is scheduled fortransmission on the uplink shared channel. Please note that this is incontrast to the transmission of an aperiodic CQI on the physical uplinkshared channel (PUSCH), there is no transport block transmissioninvolved, i.e., only physical layer transmission on PUSCH. Since the NDIwhich is usually used for HARQ process management, i.e., toggled NDIindicates initial transmission, may be reused in some implementationsfor indication of the activation state of the downlink componentcarrier(s), some new user equipment behavior may need to be defined forthese implementations.

One approach according to an embodiment of the invention is that theuser equipment ignores an uplink resource assignment indicating the(de)activation of downlink component carrier(s), when determiningwhether the NDI has been toggled compared to the value in the previoustransmission.

Alternatively, in another embodiment of the invention, the userequipment sets the NDI value for the HARQ process used for transmittingthe resource assignment indicating the (de)activation of downlinkcomponent carrier(s) to some predefined value, e.g., zero/one. As theeNodeB would be aware of this behavior, it could also set the NDI valuein the HARQ status information accordingly to the predefined value forthe HARQ process used for transmitting the resource assignmentindicating the (de)activation of downlink component carrier(s). Thisallows for a correct HARQ process management for furtherinitial/retransmission on this HARQ process.

Another embodiment of the invention relates to the implementation of theabove described various embodiments using hardware and software. It isrecognized that the various embodiments of the invention may beimplemented or performed using computing devices (processors). Acomputing device or processor may for example be general purposeprocessors, digital signal processors (DSP), application specificintegrated circuits (ASIC), field programmable gate arrays (FPGA) orother programmable logic devices, etc. The various embodiments of theinvention may also be performed or embodied by a combination of thesedevices.

Further, the various embodiments of the invention may also beimplemented by means of software modules, which are executed by aprocessor or directly in hardware. Also a combination of softwaremodules and a hardware implementation may be possible. The softwaremodules may be stored on any kind of computer readable storage media,for example RAM, EPROM, EEPROM, flash memory, registers, hard disks,CD-ROM, DVD, etc.

It should be further noted that the individual features of the differentembodiments of the invention may individually or in arbitrarycombination be subject matter to another invention.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects to be illustrative andnot restrictive.

1. An integrated circuit comprising: circuitry, which, in operation,controls: generation of resource assignment information including aplurality of bits that indicate activation or deactivation statuses ofrespective downlink component carriers, the downlink component carriersbeing secondary downlink component carriers added to a primary componentcarrier which is always activated, each of the downlink componentcarriers corresponding to one bit included in the plurality of bits, andthe one bit indicating that a corresponding downlink component carrieris to be activated or deactivated, wherein when any one bit of theplurality of bits indicates that its corresponding downlink componentcarrier is to be activated, the plurality of bits jointly indicate theactivation or deactivation statuses, a sounding reference signal (SRS)transmission request and a channel quality information (CQI) reportingrequest; transmission of the generated resource assignment information;and reception of a SRS and a CQI that are transmitted, in response tothe SRS transmission request and the CQI reporting request, on an uplinkcomponent carrier linked to one or more activated downlink componentcarriers; and at least one output coupled to the circuity, which, inoperation, outputs data.
 2. The integrated circuit according to claim 1,wherein the CQI is received for each of the one or more activateddownlink component carriers, wherein the CQI is generated for each ofthe one or more activated downlink component carriers at a communicationpartner apparatus.
 3. The integrated circuit according to claim 2,wherein the CQI is received on uplink resources assigned by thetransmitted resource assignment information.
 4. The integrated circuitaccording to claim 1, wherein the circuitry further controlstransmitting SRS configuration parameters for SRS transmission viahigher layer signaling, the SRS configuration parameters comprising aperiodicity and a sounding bandwidth.
 5. The integrated circuitaccording to claim 1, wherein the plurality of bits include at least oneunused bit.
 6. The integrated circuit according to claim 1, wherein theresource assignment information comprises a CRC field that is maskedwith a radio network temporary identifier (RNTI) assigned to a mobileterminal for the activation and deactivation of downlink componentcarriers.
 7. The integrated circuit according to claim 6, wherein atleast one codepoint of a carrier indicator field (CIF) of the resourceassignment information indicates whether the resource assignmentinformation includes a bit-mask for activating or deactivating thedownlink component carriers, or whether an uplink resource assignment isnot used for activation or deactivation of the downlink componentcarriers and only used for assigning uplink resources.